Missing from the “radar” soon after its discovery in 2010, it was found by chance again on May 8th, while on its way for one of the closest flybys of the Earth for an object of this size.
The Cheliabinsk meteorite measured no more than 20 meters when it entered the atmosphere over Russia in February 2013. The simple disintegration of the high-speed car-sized object had nevertheless been enough to blow up thousands of windows in several municipalities in the Urals, injuring more than 1,500 people. Now, imagine the damage that could be done by an asteroid the size of a house entering the atmosphere at more than 45,000 km/h. The power of the explosion would be hundreds, even thousands of times that of the atomic bomb of Hiroshima.
Rest assured, the asteroid 2010 WC9 here is not going to fall on Earth. This giant rock, whose size could be between 60 and 130 meters, will pass at about 200,000 km from earth, a distance less than half that separating us from the Moon.
Discovered on November 30, 2010 by the Catalina Sky Survey, Arizona, specialized in the detection of this type of objects, it had disappeared from the radar after ten days, as it went away and became too dim to be observed. The measurements made at the time had not made it possible to determine its return.
The asteroid was only rediscovered on May 8th by various observation programs. Only a few days before its closest flyby of the Earth on the night of Tuesday to Wednesday.
This asteroid is too small to be visible to the naked eye, but it can nevertheless already be seen on a video made by Northolt Branch Observatories, located in London. Astronomers propose to watch it again, live, Monday night, around midnight, if the weather conditions are favorable.
It is not uncommon for objects to pass as close to the Earth: 60 known objects have passed at similar distances to the Earth in 2016, 56 in 2017, 33 in 2018 so far. It is nevertheless one of the closest flybys recorded for such a big object. Coincidentally, this encounter occurs one month to the day after 2018 GE3, an asteroid of similar size, had passed at a similar distance, probably making these the two biggest objects to have brushed us so close in recent history.
What is not very reassuring, however, is that no one had been able to anticipate its arrival: it had only been discovered the day before its flyby through the Catalina Sky Survey, a time too short to anticipate or prevent the disaster it would have caused by falling on Earth.